SBC cam spec help!!??
 

New to the forum but I have a custom built 434 sbc with FAST Xfi fuel injection in a 230lx stingray with B1 outdrive (1.50) with upgrades spinning a tweaked 22p B1 wheel. With that being said the motor was "detuned" if you will in the form a smaller cam. when that took place it shifted the power curve too far down to run where the motor needs and likes to be. On the dyno it nosed over at 5800. I need to pull it up to 6000-6200 to be where i need to be. Motor specs and original and current cam specs below.

Motor:
434 Dart Little M block
Hydraulic roller motor
All forged rotating assembly
Iron RHS 228cc ported heads
69cc chambers
1.6 rockers
Compression 9.94:1
EFI edelbrock single plane manifold also port matched
Current Cam specs 220/224 @.50 .513/.528 @114lsa
Stainless marine SBC manifolds and risers with Corsa diverters to Y and thru hull (always stays through thru hull though)
made 533hp up to 5800

Original Cam:
230/236 @112 lsa
lift was around same as .513/528
made 588hp at 6300

My question is im looking at putting power back into it in terms of camshaft and retune. I am just worried about possible water reversion.
I am going to delete the factory Y and stay solely with Thru Hull but in the process of deleting the diverters (10" of SS tubing to replace) was going to extended the risers where the exhaust and water meet(have a very good fabricator/welder that can extend the water jacket style) that would put the point of intersection at 20" away from top of manifold exit. Also was thinking to help curb reversion putting a 3.5" to 3" reducer on the exhaust pipe to create more of a step that water would have to cross to get back up to motor while being farther away than current setup. Angle to transom is somewhere between 20-25*.

New Cam specs:
I speced this myself and any help on what would work would be great. I am also the one who will be tuning the new setup. I am very familiar with LSX motors but not on marine style engines.

230/236 .518/.530 @113lsa
or
230/234 @113

Trying to keep valve overlap as minimal as possible.

any help, input, suggestions, or experience would be greatly appreciated.

I am not above buying a speced cam from an engine builder that has experience. motor was already built when i bought the boat but verified everything in motor last winter. no problems with reversion with current setup. would like some more bump for my taste but need the extra power back and up 500-600 rpm to get to my goals.:cartman:

Bump for help or to get me pointed toward someone with knowledge on this

bob madera would be the guy to call.585 654 8583

go w/ the 230/236 on a 114ls

Have a picture of your current exhaust so we can see this "20-25*" angle ?

And yes, a step where the water enters the exhaust is much better than the typical inner being formed (flared out) to the outer with holes drilled for water to enter. Also, slash cut the inner so the top of inner is longer than bottom of inner. Just like slash cut tailpipes are.

Agree. However, my Tim Allen grunt wants to throw a whole lot more cam into it. LOL.

And see if they will give you more lift, assuming the lift #'s given are with 1.6's. 228cc sbc heads are not low lift 'street' heads.

BTW: sounds like a fun hotrod. Congrats !

ell he only gave me 2 to work w/ so I modded the one that would give him some umph.

I agree. I would fabricate the exhaust to allow me to run a cam the engine wants/deserves. Those are some good heads. Something tells me that combo will love more duration, more lift, and a tighter lobe separation than a 114.

thanks guys. I will actually try and get a measurement on it today. I keep it in my warehouse where it has heat since its starting to get cold here now in South Carolina. the 20-25* angle was a guestimate and did not have an eye on it at the time but will go back and try and verify that but may be eating my words on the angle the more i think of it. will try and post a pic also if that will help

and i am open to any cam suggestions not just what was posted. don't have a whole lot of experience with marine engines as they seem to be a different breed.

SB those numbers were 1.5 measurements. .547In/.563Ex @ 1.6 curently

I'm really interested to see what kind of power you make with this and where the torque comes in at. I have built a 408ci LS2 that I am putting in my boat, and I also called Bob Madera for my cam. We ended up using one that is 242/250 .621/.613 112*ls. I ended up having lightning build me a set of headers and when he built them he extended the collector out past the back of the header to help fight reversion. I can actually extend it even more if I want, but I think it'll be ok where its at. As of now, the water won't mix into the exhaust till its almost at the transom.

If it were me the 230/236 would/should work on that size motor but I would prefer a 114LSA. As SB noted you can afford more lift. For reference I'm at 221/230 on a 114LSA with .525/.545" on a 1.5 rocker in a 377 cid motor. No reversion noted to date.

I am actually waiting on a call back from Bob so i can give him exact numbers on my heads/flows/ect.. We will see what his suggestion is but from what brief conversation we had when he started my build sheet he says definitely 230s and running the riser extension the way i am going to will be perfect to fight against reversion. Will report back once i know more. Not sure if it'd be out of courteous or not to give all the specs he suggest but if he doesn't care ill let them fly. Corey, i may not know SBC marine engines very well but i do know my way around a LSX motor very well. With you running a 4"+ bore whether you are running cathedral port or rectangular port those heads react a little different to cam specs than SBCs.

trash what kind of power are you making?

Never dyno'd it but netted between 10-12 mph increase over stock 350 Mag in a beamy slow hull. I've also left power on the table with smaller runner size. I would estimate between 370-412 hp. I know that's a big bracket but that's my guess. I've been trying to prop shaft dyno it but getting the time to do it is difficult.

20 less cubes one less foot and about 800lbs less hull with a vp dp very similar sbc stroker build gets real close to 80 without going too far past 6k rpm. May have a little wiggle room for fancy exhaust water dump options with that particular exhaust set up.
A hot 434" smallblock bravo combo can dump some serious water in the exhaust

Good call working with Bob. He spec'd my last 383 cam. 234/240 .580" /.568" 112+4. Idled very nice with excellent docking manners. I ran GLM alum manifolds and Imco risers with 20" extensions mixing the water in at the tips. No reversion. Never dyno tested but 475hp was estimated. Ran very well for 475hp. I just don't see those small cams you have mentioned pulling the rpms your wanting. The above cam pulled very hard 5900-6200 rpms.

<iframe width="420" height="315" src="https://www.youtube.com/embed/rxT0vfMSJDM" frameborder="0" allowfullscreen></iframe>

OSO does embedded vid's different. Here's ryans vid

https://www.youtube.com/watch?v=rxT0vfMSJDM

Talked with him today to give him final head porting specs/valve sizes and flow numbers i had availible. Says more than likely 230s intake 240s exhaust. Im goimg to have it idle around 800-850 and he seems to think with the way i will extend the risers reversion shouldnt be an issue. So i guess we will see. Guess too many people haven't put a good bit more power in these boats? He thinks 575ish should be achievable with a stout leg in it but told him how we cruise im looking for 75-80% out of 100 on cam size vs power scale.

Ryan what did your boat idle at rpm wise? Bravo hold the gear shifts ok around the docks?

SB, Thanks for taking care of me on the vid.

Idling in N was 775-800rpms. Very smooth no stalling or hesitation. I could idle in gear down to 650-675rpms without stalling. Excellent dock manners. This was with an Alpha SS drive. These concerns were given to Bob M and he delivered on the cam. Everything I wanted and more. Your 434 would purr like a kitten with that cam.

Sounds like your working with Bob now but have you ever work'd with Comp Cam's tech? I can send you my Comp contact if your looking for a second opinion. Always treated me fair. I'm definitely interested to hear how your setup turns out. I rebuilt my 350 SBC engines with only minor upgrades (cam and heads) because I've been toying with going 427's sbc's someday. Keep us posted. AB

AB i may look into a second opinion just to see how close they match Bob's numbers but i feel pretty confident he is going to get me going in the right direction. I will keep you posted. Once a decision is made i will go ahead and have the cam ground then will turn my attention to getting risers extended. After that will be the install and i will be tuning it with some timing help from Bob. im figuring 850-800 rpm idle. idles at 800 now and 700-720 in gear. Just had a little boy December 1st so i'll be trying to juggle my time so im not away from him too much but it is most certainly happening!

Bob is the right way to go. He did my small block cam. The results were beyond my expectations.

Jeff

What ignition module did you use - I forget ?

Merc TB IV 22* advance module tied into a MSD 6AL.